After analyzing the features of species mass in engine combustion process, considering the accuracy and calculating time together, based on a network for one specie, this paper proposes an algorithm for selecting RBF-ANN centers with sectional method to apply in engine combustion species mass: in the image of species mass fraction-temperature, mass fraction area is divided into N parts dynamically, temperature area is divided into 6 fixed parts, then selects a sample as RBF-ANN center in every overlapped area of vertical (mass fraction) area and horizontal (temperature) area. Through calculating 135 diesel combustion process, it shows that the accuracy of function approximation has been improved greatly with sectional method, compared with subtractive cluster method.